The 7.5 cm KwK 40 (7.5 cm Kampfwagenkanone[a] 40) was a German 75 mm Second World War era vehicle-mounted gun, used as the primary armament of the German Panzer IV (F2 model onwards) medium tank and the Sturmgeschütz III (F model onwards) and Sturmgeschütz IV assault guns which were used as tank destroyers.

It replaced the 7.5 cm KwK 37 with its 24-calibre barrel, providing a huge improvement in firepower for mid-war tank designs.

Along with the Pak 40, the KwK 40/StuK 40 was the most numerous anti-tank gun of the German army, and remained an effective weapon until the war's end.

When mounted on a casemate-armored assault gun-designated vehicle (Sturmgeschütz)) instead of a turreted tank, the weapon was called Sturmkanone 40 (StuK 40).

The designs progressed from tubular type double baffle muzzle brakes to single baffle ball shape muzzle brakes, which proved to be insufficient in reducing recoil, followed by a double flange type from May 1943.